A simple SPICE macro model has been created for ESD MOS modeling. The model consists of standard components only. It includes a MOS transistor modeled by BSIM3v3, a bipolar transistor modeled by VBIC, and a resistor for substrate resistance. It offers advantages of convenience in CAD implementation, high simulation speed, wider availability, and less convergence issues. The modeling approach has been used to investigate rise-time effects in TLP stress testing. The simulation demonstrated that the rising edge of TLP pulse has impact on snapback trigger voltage Vt1 not only in gate coupled NMOS but also grounded gate NMOS devices.